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ZigBEE. Fundamentals of ZigBee. Low Cost Low Power Security-enabled Reliable Initial Target Markets were AMR, Building Automation, and Industrial Automation (M2M Comms). ZigBee Protocol. Where Does ZigBee Fit? Data Rate vs. Range vs. Battery Life (not shown). Wireless Video Applications.

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ZigBEE

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ZigBEE


Fundamentals of ZigBee

Low Cost

Low Power

Security-enabled

Reliable

Initial Target Markets were AMR, Building Automation, and Industrial Automation (M2M Comms)


ZigBee Protocol

Where Does ZigBee Fit?

Data Rate vs. Range vs. Battery Life (not shown)

Wireless Video Applications

Faster

Video

UWB

Data

Wireless Data Applications

802.11g

802.11a

IrDA

Wi-Fi®

Voice

Peak Data Rate

802.11b

Cellular

2.5G/3G

Bluetooth™

Monitoring

& Control

Data

Transfer

ZigBee™

Slower

Wireless Networking

Closer

Farther

Range


Wireless Standards Comparison


The Value of Mesh:Extending Range

  • out of range, no RF connectivity

  • Point-to-Multipoint

  • Reduced Function Device

  • Communications Flow


The Value of Mesh:Extending Range

  • leverage network nodes to increase range and establish RF connectivity

  • Mesh Node Hopping

  • RF Node

  • Communications Flow


The Value of Mesh:Self Healing/Discovery

  • unexpected interruptions in the network can be automatically compensated for by re-directing communication

  • Mesh Node Hopping

  • RF Node

  • Communications Flow


Section 1

Zigbee Pro Feature Set


ZigBee Feature Sets

  • ZigBee releases are defined as “Feature Sets”

    • A Feature Set refers to a group, or set, of features. There are two Feature Sets in the latest update to the ZigBee specification: ZigBee Feature Set and the ZigBee PRO Feature Set.

  • “ZigBee 2004”, “ZigBee 2006”, and “ZigBee 2007” are colloquial references and not endorsed by the ZigBee Alliance


  • ZigBee Events

  • ZigBee Technology

  • ZigBee PRO Feature Set available

  • “Smart Energy” profile ratified

  • ZigBee Feature Set available

  • IEEE 802.15.4 released

  • ZigBee “2004” ratified

  • ZigBee “2004” available

  • Need for WPANs

  • 2003

  • 2004

  • 2005

  • 2006

  • 2007

  • 2008

  • “Enhanced” mesh; pseudo-stochastic addressing; support for more dense networks; compatibility issues

  • Point-to-multipoint / peer-to-peer networks

  • Feeble,

  • mesh networking; tree-based addressing architecture; very small node density

  • Significantly improved mesh; support for thousands of nodes; broad interoperability


ZigBee Feature Set (2004)

  • Coordinator

  • Router

  • Tree Mesh

  • Reduced Function Device

  • Communications Flow


ZigBee Pro Feature Set

  • Coordinator

  • Router

  • Stochastic Mesh

  • Reduced Function Device

  • Communications Flow


ZigBee & IEEE 802.15.4

  • ZigBee uses the PHY and MAC defined by 802.15.4

  • Accordingly, ZigBee is a WPAN network, but with added networking intelligence

  • ZigBee inherits the RF characteristics of its 802.15.4 platform:

    • RF Link Budget

    • Current Draw


Simplified ZigBee Stack

  • User defined

  • User Application

  • ZigBee Device Object (ZDO)

  • ZigBee APS

  • Security Services

  • ZigBee Protocol

  • ZigBee Network Layer

  • MAC

  • IEEE 802.15.4

  • PHY

  • (2.4 GHz, 900 MHz, 868 MHz)


802.15.4 Protocol

802.15.4 Specifications

Supported Networks

Point-Point

Point-Multipoint/Star

Types of Nodes

Coordinator

End Node

Reliable Delivery

CSMA/CA

MAC-level (pt-pt) Retries/Acknowledgments

64-bit IEEE and 16-bit short Addressing

16 DSSS RF Channels

ZigBee AF

ZigBee

ZDO

ZigBee APS

ZigBee Network

802.15.4 MAC

802.15.4 PHY


802.15.4 Protocol

802.15.4 Nodes in a PAN (Personal Area Network)


ZigBee Protocol

Supported Networks

Point-Point

Point-Multipoint/Star

MESH

Types of Nodes

Coordinator

End Node

ROUTER

Reliable Delivery

CSMA/CA

MAC-level (pt-pt) Retries/Acknowledgments

MESH NETWORK-level (multi-hop) Retries/ACKs

16 DSSS RF Channels

ZigBee AF

ZigBee

ZDO

ZigBee APS

ZigBee Network

802.15.4 MAC

802.15.4 PHY


ZigBee Protocol

ZigBee Nodes in a PAN (Personal Area Network)

  • Coordinator

  • One per PAN

  • Establishes/Organizes a PAN

  • Mains-powered

  • Router

  • Optional

  • Several can be in a PAN

  • Mains-powered

  • End Device

  • Several can be in a PAN

  • Low power


ZigBee Protocol

ZigBee Specifications

Addressing

64-bit IEEE Address

Unique to every 802.15.4 device in the world

Permanent, assigned during mfg

16-bit Network Addressing

Unique to each module within a PAN

Used in Routing Tables

Used for data transmissions, etc.

Volatile Address - Can Change

ZigBee AF

ZigBee

ZDO

ZigBee APS

ZigBee Network

802.15.4 MAC

802.15.4 PHY


802.15.4 Data Transmission modes

Broadcast Mode

To send a broadcast packet to all radios regardless of 16-bit or 64-bit addressing

Unicast Mode – Guaranteed Delivery

64-bit IEEE Addressing

Destination 64-bit Address to match 64-bit source address of intended receiver.

16-bit Network Addressing

Destination 16-bit Address to match 16-bit source address of intended receiver

ZigBee Protocol needs/uses


PAN Network Formation

Coordinator must select an unused operating channel and PAN ID

Energy scan on all channels

Sends Beacon request (Broadcast PAN ID)

Listens to all responses and logs the results

After the Coordinator has started, it will allow nodes to join to it for a time based on the specified Node Join Time

ZigBee Protocol


Router Startup

A new Router must locate a Router that has already joined a PAN or a Coordinator

Sends a Broadcast PAN ID on each channel

Returns sent via Unicast

Router will then try to join to a Router or Coordinator that is allowing joining

ZigBee Protocol


End node: Low-power Sleep Modes

End Node Startup

A new End node must locate a Router that has already joined a PAN or a Coordinator

Sends a Broadcast PAN ID on each channel

Returns sent via Unicast

End node will then try to join to a parent (Router or Coordinator) that is allowing joining

ZigBee Protocol


Single Point of Failure

Common Belief:

If a Coordinator fails, the network fails

FALSE:

If a Coordinator fails, the network continues to function, but without certain non-essential features of the Coordinator


ZigBee Protocol

  • Broadcast Transmissions - Relayed to All Nodes

    • No Acks are transmitted – Routers listen to neighboring Routers to know if message was retransmitted

    • Retransmit if neighbors are not heard (up to 2 times)

    • Broadcast Transaction Table used to ensure Routers do not repeat a message they have already repeated

    • Expensive time wise

R

R

R

R

R

C

R

R

R

R


ZigBee Protocol

  • Route Discovery consists of the following commands:

    • Route Request (broadcast)

      • 64-bit address used to find the local 16-bit address (Network address discovery)

      • Routing tables based on 16-bit address

    • Route Reply (unicast)

      • Positive acknowledgement returned

      • If node is gone- Network address discovery fails

R7

R2

C

R6

R1

R10

R3

R5


ZigBee Protocol

  • Normal Data Transmissions (Unicast - established Network)

    • R1 must transmit data to R10.

    • MAC ACKs are transmitted for each hop.

    • One Network ACK is transmitted from the Destination node back to the Source

R1

R7

R8

R2

R9

C

R6

R4

R3

R10

R5


ZigBee Protocol

Disabled Node

R1

X

R7

R8

R2

R9

C

R6

R4

R3

R10

R5


ZigBee Protocol

  • Disabled Node

    • New Route Discovery Request (broadcast)

      • 64-bit address used to find the local 16-bit address (Network address discovery)

R1

X

R7

R8

R2

R9

C

R6

R4

R3

R10

R5


ZigBee Protocol

  • Disabled Node

    • New Route sent back along best path (unicast)

    • Coordinator not necessary after network setup

R1

X

R7

R8

R2

R9

C

R6

R4

R3

R10

R5


ZigBee Protocol

  • Sleeping end node (child)

    • Associates with a parent

      • Parent takes over Zigbee network communications while child is sleeping

      • Parent must always be awake (router or coordinator)

      • Number of childs per parent is limited

R1

R7

R8

R2

R9

C

R6

R4

R3

E10

R5


Section 2

Digimesh


The Value of Mesh

  • many common mesh technologies require different node types with a parent/child relationship to achieve mesh node hopping

  • Coordinator

  • Router

  • Mesh Node Hopping

  • Reduced Function Device

  • Communications Flow


DigiMesh Topology

  • Peer-to-Peer Mesh

  • DigiMesh Router

  • Communications Flow


DigiMesh Network Overview

  • Simple relative to Parent/Child-based mesh technologies

  • Support for Sleeping Routers

  • Unpredictable timing (like all mesh networks)

  • Poor latency performance relative to multipoint technologies (like all mesh networks)

  • Lower sustained throughput relative to multipoint products (like all mesh networks)


How DigiMesh is Different

Parent/Child Mesh

DigiMesh

Peer-to-Peer Hierarchy

One Node Type

Support for Sleeping Routers

Simple Setup

900 MHz and 2.4 GHz

Proprietary Protocol

  • Parent/Child Hierarchy

  • Multiple Node Types

  • No Sleeping Routers

  • Complex Setup

  • Most Commonly 2.4 GHz

  • Open Protocols Available


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